OMG! The tool is awesome! But it seems doesn't work well if I use it within my notes, it is akin to being stuck at the loading process, but it's fine when I opened a blank note for it.
I really love this tool, as my suggestion, I think it better run on a new dialog window, and then save images at once to the notes. Joplin has 2 similar plugins that are worth reference Draw.io and Freehand Drawing.
Thank you again, you brought in a great tool! 